package net.danielthompson.danray.shading;

/**
 * DanRay
 * User: dthompson
 * Date: 7/3/13
 * Time: 3:45 PM
 */
import java.awt.Color;

/**
 *  The HSLColor class provides methods to manipulate HSL (Hue, Saturation
 *  Luminance) values to create a corresponding Color object using the RGB
 *  ColorSpace.
 *
 *  The HUE is the color, the Saturation is the purity of the color (with
 *  respect to grey) and Luminance is the brightness of the color (with respect
 *  to black and white)
 *
 *  The Hue is specified as an angel between 0 - 360 degrees where red is 0,
 *  green is 120 and blue is 240. In between you have the colors of the rainbow.
 *  Saturation is specified as a percentage between 0 - 100 where 100 is fully
 *  saturated and 0 approaches gray. Luminance is specified as a percentage
 *  between 0 - 100 where 0 is black and 100 is white.
 *
 *  In particular the HSL color space makes it easier change the Tone or Shade
 *  of a color by adjusting the luminance value.
 */
public class HSLColor
{
   private Color rgb;
   private float[] hsl;
   private float alpha;

   /**
    *  Create a HSLColor object using an RGB Color object.
    *
    *  @param rgb the RGB Color object
    */
   public HSLColor(Color rgb)
   {
      this.rgb = rgb;
      hsl = fromRGB( rgb );
      alpha = rgb.getAlpha() / 255.0f;
   }

   /**
    *  Create a HSLColor object using individual HSL values and a default
    * alpha value of 1.0.
    *
    *  @param h is the Hue value in degrees between 0 - 360
    *  @param s is the Saturation percentage between 0 - 100
    *  @param l is the Lumanance percentage between 0 - 100
    */
   public HSLColor(float h, float s, float l)
   {
      this(h, s, l, 1.0f);
   }

   /**
    *  Create a HSLColor object using individual HSL values.
    *
    *  @param h     the Hue value in degrees between 0 - 360
    *  @param s     the Saturation percentage between 0 - 100
    *  @param l     the Lumanance percentage between 0 - 100
    *  @param alpha the alpha value between 0 - 1
    */
   public HSLColor(float h, float s, float l, float alpha)
   {
      hsl = new float[] {h, s, l};
      this.alpha = alpha;
      rgb = toRGB(hsl, alpha);
   }

   /**
    *  Create a HSLColor object using an an array containing the
    *  individual HSL values and with a default alpha value of 1.
    *
    *  @param hsl  array containing HSL values
    */
   public HSLColor(float[] hsl)
   {
      this(hsl, 1.0f);
   }

   /**
    *  Create a HSLColor object using an an array containing the
    *  individual HSL values.
    *
    *  @param hsl  array containing HSL values
    *  @param alpha the alpha value between 0 - 1
    */
   public HSLColor(float[] hsl, float alpha)
   {
      this.hsl = hsl;
      this.alpha = alpha;
      rgb = toRGB(hsl, alpha);
   }

   /**
    *  Create a RGB Color object based on this HSLColor with a different
    *  Hue value. The degrees specified is an absolute value.
    *
    *  @param degrees - the Hue value between 0 - 360
    *  @return the RGB Color object
    */
   public Color adjustHue(float degrees)
   {
      return toRGB(degrees, hsl[1], hsl[2], alpha);
   }

   /**
    *  Create a RGB Color object based on this HSLColor with a different
    *  Luminance value. The percent specified is an absolute value.
    *
    *  @param percent - the Luminance value between 0 - 100
    *  @return the RGB Color object
    */
   public Color adjustLuminance(float percent)
   {
      return toRGB(hsl[0], hsl[1], percent, alpha);
   }

   /**
    *  Create a RGB Color object based on this HSLColor with a different
    *  Saturation value. The percent specified is an absolute value.
    *
    *  @param percent - the Saturation value between 0 - 100
    *  @return the RGB Color object
    */
   public Color adjustSaturation(float percent)
   {
      return toRGB(hsl[0], percent, hsl[2], alpha);
   }

   /**
    *  Create a RGB Color object based on this HSLColor with a different
    *  Shade. Changing the shade will return a darker color. The percent
    *  specified is a relative value.
    *
    *  @param percent - the value between 0 - 100
    *  @return the RGB Color object
    */
   public Color adjustShade(float percent)
   {
      float multiplier = (100.0f - percent) / 100.0f;
      float l = Math.max(0.0f, hsl[2] * multiplier);

      return toRGB(hsl[0], hsl[1], l, alpha);
   }

   /**
    *  Create a RGB Color object based on this HSLColor with a different
    *  Tone. Changing the tone will return a lighter color. The percent
    *  specified is a relative value.
    *
    *  @param percent - the value between 0 - 100
    *  @return the RGB Color object
    */
   public Color adjustTone(float percent)
   {
      float multiplier = (100.0f + percent) / 100.0f;
      float l = Math.min(100.0f, hsl[2] * multiplier);

      return toRGB(hsl[0], hsl[1], l, alpha);
   }

   /**
    *  Get the Alpha value.
    *
    *  @return the Alpha value.
    */
   public float getAlpha()
   {
      return alpha;
   }

   /**
    *  Create a RGB Color object that is the complementary color of this
    *  HSLColor. This is a convenience method. The complementary color is
    *  determined by adding 180 degrees to the Hue value.
    *  @return the RGB Color object
    */
   public Color getComplementary()
   {
      float hue = (hsl[0] + 180.0f) % 360.0f;
      return toRGB(hue, hsl[1], hsl[2]);
   }

   /**
    *  Get the Hue value.
    *
    *  @return the Hue value.
    */
   public float getHue()
   {
      return hsl[0];
   }

   /**
    *  Get the HSL values.
    *
    *  @return the HSL values.
    */
   public float[] getHSL()
   {
      return hsl;
   }

   /**
    *  Get the Luminance value.
    *
    *  @return the Luminance value.
    */
   public float getLuminance()
   {
      return hsl[2];
   }

   /**
    *  Get the RGB Color object represented by this HDLColor.
    *
    *  @return the RGB Color object.
    */
   public Color getRGB()
   {
      return rgb;
   }

   /**
    *  Get the Saturation value.
    *
    *  @return the Saturation value.
    */
   public float getSaturation()
   {
      return hsl[1];
   }

   public String toString()
   {
      String toString =
            "HSLColor[h=" + hsl[0] +
                  ",s=" + hsl[1] +
                  ",l=" + hsl[2] +
                  ",alpha=" + alpha + "]";

      return toString;
   }

   /**
    *  Convert a RGB Color to it corresponding HSL values.
    *
    *  @return an array containing the 3 HSL values.
    */
   public static float[] fromRGB(Color color)
   {
      //  Get RGB values in the range 0 - 1

      float[] rgb = color.getRGBColorComponents( null );
      float r = rgb[0];
      float g = rgb[1];
      float b = rgb[2];

      //	Minimum and Maximum RGB values are used in the HSL calculations

      float min = Math.min(r, Math.min(g, b));
      float max = Math.max(r, Math.max(g, b));

      //  Calculate the Hue

      float h = 0;

      if (max == min)
         h = 0;
      else if (max == r)
         h = ((60 * (g - b) / (max - min)) + 360) % 360;
      else if (max == g)
         h = (60 * (b - r) / (max - min)) + 120;
      else if (max == b)
         h = (60 * (r - g) / (max - min)) + 240;

      //  Calculate the Luminance

      float l = (max + min) / 2;
      //System.out.println(max + " : " + min + " : " + l);

      //  Calculate the Saturation

      float s;

      if (max == min)
         s = 0;
      else if (l <= .5f)
         s = (max - min) / (max + min);
      else
         s = (max - min) / (2 - max - min);

      return new float[] {h, s * 100, l * 100};
   }

   /**
    *  Convert HSL values to a RGB Color with a default alpha value of 1.
    *  H (Hue) is specified as degrees in the range 0 - 360.
    *  S (Saturation) is specified as a percentage in the range 1 - 100.
    *  L (Lumanance) is specified as a percentage in the range 1 - 100.
    *
    *  @param hsl an array containing the 3 HSL values
    *
    *  @returns the RGB Color object
    */
   public static Color toRGB(float[] hsl)
   {
      return toRGB(hsl, 1.0f);
   }

   /**
    *  Convert HSL values to a RGB Color.
    *  H (Hue) is specified as degrees in the range 0 - 360.
    *  S (Saturation) is specified as a percentage in the range 1 - 100.
    *  L (Lumanance) is specified as a percentage in the range 1 - 100.
    *
    *  @param hsl    an array containing the 3 HSL values
    *  @param alpha  the alpha value between 0 - 1
    *
    *  @returns the RGB Color object
    */
   public static Color toRGB(float[] hsl, float alpha)
   {
      return toRGB(hsl[0], hsl[1], hsl[2], alpha);
   }

   /**
    *  Convert HSL values to a RGB Color with a default alpha value of 1.
    *
    *  @param h Hue is specified as degrees in the range 0 - 360.
    *  @param s Saturation is specified as a percentage in the range 1 - 100.
    *  @param l Lumanance is specified as a percentage in the range 1 - 100.
    *
    *  @returns the RGB Color object
    */
   public static Color toRGB(float h, float s, float l)
   {
      return toRGB(h, s, l, 1.0f);
   }

   /**
    *  Convert HSL values to a RGB Color.
    *
    *  @param h Hue is specified as degrees in the range 0 - 360.
    *  @param s Saturation is specified as a percentage in the range 1 - 100.
    *  @param l Lumanance is specified as a percentage in the range 1 - 100.
    *  @param alpha  the alpha value between 0 - 1
    *
    *  @returns the RGB Color object
    */
   public static Color toRGB(float h, float s, float l, float alpha)
   {
      if (s <0.0f || s > 100.0f)
      {
         String message = "Color parameter outside of expected range - Saturation";
         throw new IllegalArgumentException( message );
      }

      if (l <0.0f || l > 100.0f)
      {
         String message = "Color parameter outside of expected range - Luminance";
         throw new IllegalArgumentException( message );
      }

      if (alpha <0.0f || alpha > 1.0f)
      {
         String message = "Color parameter outside of expected range - Alpha";
         throw new IllegalArgumentException( message );
      }

      //  Formula needs all values between 0 - 1.

      h = h % 360.0f;
      h /= 360f;
      s /= 100f;
      l /= 100f;

      float q;

      if (l < 0.5)
         q = l * (1 + s);
      else
         q = (l + s) - (s * l);

      float p = 2 * l - q;

      float r = Math.max(0, HueToRGB(p, q, h + (1.0f / 3.0f)));
      float g = Math.max(0, HueToRGB(p, q, h));
      float b = Math.max(0, HueToRGB(p, q, h - (1.0f / 3.0f)));

      r = Math.min(r, 1.0f);
      g = Math.min(g, 1.0f);
      b = Math.min(b, 1.0f);

      return new Color(r, g, b, alpha);
   }

   private static float HueToRGB(float p, float q, float h)
   {
      if (h < 0) h += 1;

      if (h > 1 ) h -= 1;

      if (6 * h < 1)
      {
         return p + ((q - p) * 6 * h);
      }

      if (2 * h < 1 )
      {
         return  q;
      }

      if (3 * h < 2)
      {
         return p + ( (q - p) * 6 * ((2.0f / 3.0f) - h) );
      }

      return p;
   }
}